This invention relates generally to monitoring systems and more particularly concerns devices and systems used to monitor bed patients in hospital or other care giving environments.
It is well documented that the elderly and post-surgical patients are at a heightened risk of falling. There are many reasons for this but, broadly speaking, these individuals are often afflicted by gait and balance disorders, weakness, dizziness, confusion, visual impairment, and postural hypotension (i.e., a sudden drop in blood pressure that causes dizziness and fainting), all of which are recognized as potential contributors to a fall. Additionally, cognitive and functional impairment, and sedating and psychoactive medications are also well recognized risk factors.
A fall places the patient at risk of various injuries including sprains, fractures, and broken bonesxe2x80x94injuries which in some cases can be severe enough to eventually lead to a fatality. Of course, those most susceptible to falls are often those in the poorest general health and least likely to recover quickly from their injuries. In addition to the obvious physiological consequences of fall-related injuries, there are also a variety of adverse economic and legal consequences that include the actual cost of treating the victim and, in some cases, caretaker liability issues.
In the past, it has been commonplace to treat patients that are prone to falling by limiting their mobility through the use of restraints, the underlying theory being that if the patient is not free to move about, he or she will not be as likely to fall. However, research has shown that restraint-based patient treatment strategies are often more harmful than beneficial and should generally be avoidedxe2x80x94the emphasis today being on the promotion of mobility rather than immobility. Among the more successful mobility-based strategies for fall prevention include interventions to improve patient strength and functional status, reduction of environmental hazards, and staff identification and monitoring of high-risk hospital patients and nursing home residents.
Of course, monitoring high-risk patients, as effective as that care strategy might appear to be in theory, suffers from the obvious practical disadvantage of requiring additional staff if the monitoring is to be in the form of direct observation. Thus, the trend in patient monitoring has been toward the use of electrical devices to signal changes in a patient""s circumstance to a caregiver who might be located either nearby or remotely at a central monitoring facility, such as a nurse""s station. The obvious advantage of an electronic monitoring arrangement is that it frees the caregiver to pursue other tasks away from the patient. Additionally, when the monitoring is done at a central facility a single nurse can monitor multiple patients which can result in decreased staffing requirements.
Generally speaking, electronic monitors work by first sensing an initial status of a patient, and then generating a signal when that status changes, e.g., he or she has sat up in bed, left the bed, risen from a chair, etc., any of which situations could pose a potential cause for concern in the case of an at-risk patient. Electronic bed and chair monitors typically use a pressure sensitive switch in combination with a separate monitor /microprocessor. In a common arrangement, a patient""s weight resting on a pressure sensitive mat (i.e., a xe2x80x9csensingxe2x80x9d mat) completes an electrical circuit, thereby signaling the presence of the patient to the microprocessor. When the weight is removed from the pressure sensitive switch, the electrical circuit is interrupted, which fact is sensed by the microprocessor. The software logic that drives the monitor is typically programmed to respond to the now-opened circuit by triggering some sort of alarmxe2x80x94either electronically (e.g., to the nursing station via a conventional nurse call system) or audibly (via a built-in siren). Some examples of devices that operate in this general fashion may be found in U.S. Pat. Nos. 4,484,043, 4,565,910, 5,554,835, and 5,634,760, the disclosures of which are incorporated herein by reference.
That being said, patient monitoring systems that rely on sensor mats to detect the presence of a patient in a bed suffer from a variety of drawbacks. For example, the bed monitoring systems currently available in the marketplace feature externally accessible configuration switches that allow the caregiver to reconfigure the device at will and to adjust parameters such as the duration of the alarm, and the time lapse between the sensing of the xe2x80x9cempty bedxe2x80x9d condition and the sounding of an alarm. External switching makes tampering with the system extremely easy and makes it more difficult to establish and maintain a hospital-wide policy with respect to monitor settings.
A further problem with conventional bed monitoring systems is that they use oscillating transducers in their alarm audio circuits, resulting in single frequency audio alarms. Since bed monitor alarms are frequently employed in environments in which a multiplicity of other problems might also trigger audio alarms, if the single alarm sound provided by the bed monitor happens to be similar to one or more other alarm sounds heard in response to different monitors, confusion and consequential lengthened response times to patient monitor alarms may result.
Those skilled in the art know that there are many nurse call station configurations and it is to the economic advantage of a manufacturer to be able to accommodate all of them. However, another problem with the present state-of-the-art in bed monitoring systems is that they are typically pre-configured internally at the factory for one particular type of nurse call station. Thus, if the unit is misconfigured when it arrives at an installation, it may be necessary to summon a medical technician to reconfigure it, since internal modifications to the unit are required to adapt it to different call station types. This can result in additional expense and delay in getting the unit correctly configured and into operation. Further, there are many hospitals that use multiple incompatible nurse call system types, each having been separately added as a new building or wing was constructed. The inability to quickly and reliably move electronic monitors between these systems means that the hospital will generally be required to maintain excess inventory of each type of compatible monitor, a result that ultimately adds to the health care costs borne by the consumer/patient.
Still another failure in known bed monitoring systems is that they do not provide a method of accumulating statistical data relating to the operation of the unit including, for example, the response times of the caregiver to alarm conditions. This sort of information could be very helpful to the maintenance and proper operation of the monitor, and for caregiver quality control purposes.
It is, therefore, a primary object of this invention to provide a patient monitor that is microprocessor-based so as to be reconfigurable by the uploading of configuration data to an electronically erasable programmable read only memory accessible by the microprocessor. A further object of this invention is to provide a microprocessor based patient monitor which synthesizes multiple alarm sounds in software for selection by the caregiver. It is also an object of this invention to provide a microprocessor based patient monitor having a nurse call interface allowing interconnection with any nurse call station without modification of the monitor. Yet another object of this invention is to provide a microprocessor based patient monitor having an electrically erasable programmable read only memory accessible by the microprocessor for logging statistical data with respect to the use of the monitor and the response time of the caregiver who is responding to the alarm. Another object of this invention is to provide a microprocessor based bed patient monitor which permits the downloading of the logged statistical data to a host microprocessor connected to the system. It is still another object of the instant invention to provide a system for configuration of monitor parameters and for recalling and analyzing statistical data accumulated therein.
Heretofore, as is well known in the bed monitor arts, there has been a need for an invention to address and solve the above-described problems. Accordingly, it should now be recognized, as was recognized by the present inventor, that there exists, and has existed for some time, a very real need for a electronic patient monitor that would address and solve the above-described problems.
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or preferred embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.
In accordance with the invention, a patient monitor is provided in which a processor receiving electronic signals from a sensor indicating the presence on the sensor and absence from the sensor of a patient is combined with an alarm system which includes a loudspeaker driven by a power amplifier which responds to an input signal derived from a programmable volume control to produce an aural alarm. The processor synthesizes at least one and preferably multiple alarm sounds under software control, operates the programmable volume control of the alarm system to select the decibel level of the alarm and activates and deactivates the alarm in response to the electronic signals received from the sensor and a user interface. An electrically erasable programmable read-only memory (or similar nonvolatile memory) accessible by the processor stores a plurality of alarm sounds for selection by the processor for synthesis of the selected alarm sound. In addition, the electrically erasable programmable read-only memory stores multiple decibel levels for selection by the processor of the desired decibel level of the alarm sound. In the preferred embodiment, the patient monitor will be used to sense the presence of patient who is lying in a bed, however, it should be noted and remembered this monitor could also be used in other sorts of applications, including with chair and toilet monitors.
Preferably, the electrically erasable programmable read-only memory also permits storage of a plurality of options for the delay time between initiation of the absence of a patient from the sensor and the activation of the alarm by the processor. Furthermore, the monitor is preferably provided with an external switch connected to the processor for caregiver selection of the delay time from the plurality of delay time options.
It is also preferred that the electrically erasable programmable read-only memory log usage data with respect to the monitor including the total hours of use of the monitor, the total time of alarms sounded by the monitor, the total number of alarms sounded by the monitor and the response time between the most recent sounding of an alarm and a subsequent operation of the monitor by the responding caregiver. The monitor will include a port for downloading the log usage data to a host computer.
The monitor also includes a nurse call interface having a relay which is energized when the power amplifier is de-energized and which has a normally opened contact, a normally closed contact and a common contact for interconnecting the monitor to a nurse call system to one of the normally opened and normally closed contacts so that the monitor requires no modification to accommodate the type of nurse call station with which the monitor is used.
According to still another aspect of the instant invention, there is provided a bed monitor/computer system which allows easy on-site configuration of a monitor to work with different nurses stations. In more particular, the monitor of the instant invention is designed to be reconfigured through the use of a host computer, which obviates the need for internal modifications of monitor parameters through the use of dip switches, rotary dials, etc., which are commonly used in the industry. In the preferred embodiment, a standard computer interface, such as serial interface, is provided as a means for communication between the monitor and a separate host computer. This allows the unit to be readily reprogrammed without risking the exposure of the internal electronic components to the environment.
According to still a further aspect of the instant invention, there is taught hereinafter a software system for providing the monitor with new programming instructions or a new xe2x80x9cpersonalityxe2x80x9d which will enable it to operate with potentially any plug-compatible nurse call station. In the preferred embodiment, the internal operating logic and various parameters which change the operation of the device to match a particular nurse call station are preferably stored in nonvolatile flash-type RAM which is RAM that can be modified on demand through the use of a host computer-to-patient monitor transfer. One obvious advantage of this arrangement is that it eliminates the many problems associated with mechanical configuration switches, such as dip switches and rotary dials, while providing an easy, inexpensive, and reliable way of upgrading or otherwise modifying the functionality of a monitor while it is in the field.
The foregoing has outlined in broad terms the more important features of the invention disclosed herein so that the detailed description that follows may be more clearly understood, and so that the contribution of the instant inventor to the art may be better appreciated. The instant invention is not to be limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. Rather, the invention is capable of other embodiments and of being practiced and carried out in various other ways not specifically enumerated herein. Additionally, the disclosure that follows is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. Further, it should be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting, unless the specification specifically so limits the invention.
While the instant invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.